Power spectra of shear-waves for eighteen earthquakes from the Anza-Imperial Valley region were inverted for source, mid-path Q, site attenuation and site response. The motivation was whether differences in site attenuation (parameterized as t*, r/cQ, where r is distance along ray path near the site, c is shear velocity and Q is the quality factor that parameterizes attenuation) and site response could be correlated with residuals in peak values of velocity or acceleration after removing the affect of distance-dependent attenuation. We decomposed spectra of S-waves from horizontal components of 18 earthquakes from 2010 to 2018 into a common source for each event with ω −2 spectral fall-off at high frequencies and then projected the residuals onto path and site terms following the methodology of Boatwright et al. (Bull Seismol Soc Am 81:1754–1782, 1991). The site terms were constrained to have an amplification at a particular frequency governed by V S30 at two of the sites which had downhole shear-wave logs. The 18 events, 3 < M < 4, had moments between approximately 10 20 and 10 22 dyne-cm, and stress drops between 1 and 100 bars. Average mid-crust attenuation had a Q of 844 reflecting the average path through the crystalline rock of the San Jacinto Mountains. t* for each station corresponded to the geologic environment such that stations on hard rock had low t* (e.g. stations KNW, PFO and RDM) a station in the San Jacinto fault zone (station SND) had a moderate t* of 0.035 s and stations in the Imperial Valley usually had higher t*s . Generally t* correlated with average amplification suggesting that sites characterized by low surface velocities and higher attenuation also have more amplification in the 1–6 Hz band. Residuals of peak values were determined by subtracting the prediction of Boore and Atkinson ( 2008 ). There is a correlation between average amplification and peak velocity, but not peak acceleration. Interestingly, there is less scatter at high values of amplification although there is also less data. Scatter in values of peak velocity and peak acceleration are higher at shorter compared to longer durations. When using a frequency-dependent form for Q , variances are higher, sometimes much higher; the dataset does not support frequency-dependent Q , which is not similar to results from the Imperial Valley and northeastern North America.

中文翻译：

---

加利福尼亚州安扎和帝王谷的峰值地面运动和场地响应

来自 Anza-Imperial Valley 地区的 18 次地震的横波功率谱被反转为震源、中径 Q、站点衰减和站点响应。动机是站点衰减（参数化为 t*、r/cQ，其中 r 是站点附近沿射线路径的距离，c 是剪切速度，Q 是参数化衰减的质量因子）和站点响应的差异是否可以与去除与距离相关的衰减影响后速度或加速度峰值中的残差。我们将 2010 年至 2018 年 18 次地震的水平分量的 S 波频谱分解为每个事件的公共源，在高频下具有 ω -2 频谱衰减，然后按照Boatwright 的方法将残差投影到路径和站点项上等。(Bull Seismol Soc Am 81:1754–1782, 1991）。站点项被限制为在由 V S30 控制的特定频率下在两个具有井下剪切波测井的站点处进行放大。18 个事件，3 < M < 4，具有大约在 10 20 到 10 22 达因-厘米之间的力矩，并且应力降在 1 到 100 巴之间。平均中地壳衰减的 Q 值为 844，反映了通过圣哈辛托山脉结晶岩的平均路径。每个台站的 t* 对应于地质环境，因此硬岩台站的 t* 较低（例如，KNW、PFO 和 RDM 台站）圣哈辛托断层带（SND 台站）中的台站具有 0.035 秒的中等 t* 和帝王谷的车站通常有更高的 t*s 。通常，t* 与平均放大率相关，这表明以低表面速度和更高衰减为特征的站点在 1-6 Hz 波段也有更多的放大率。通过减去 Boore 和 Atkinson (2008) 的预测来确定峰值的残差。平均放大率与峰值速度之间存在相关性，但与峰值加速度无关。有趣的是，尽管数据也较少，但在高放大值时分散较少。与较长的持续时间相比，较短的峰值速度和峰值加速度值的分散更高。当 Q 使用频率相关形式时，方差更高，有时更高；该数据集不支持频率相关的 Q ，这与来自帝王谷和北美东北部的结果不同。